title: Multilayer integral method for simulation of eddy currents in thin volumes of arbitrary geometry produced by MRI gradient coils.
abstract: OBJECTIVE
  This article aims to present a fast, efficient and accurate multi-layer integral method (MIM) for the evaluation of complex spatiotemporal eddy currents in nonmagnetic and thin volumes of irregular geometries induced by arbitrary arrangements of gradient coils.
  
  
  METHODS
  The volume of interest is divided into a number of layers, wherein the thickness of each layer is assumed to be smaller than the skin depth and where one of the linear dimensions is much smaller than the remaining two dimensions. The diffusion equation of the current density is solved both in time-harmonic and transient domain.
  
  
  RESULTS
  The experimentally measured magnetic fields produced by the coil and the induced eddy currents as well as the corresponding time-decay constants were in close agreement with the results produced by the MIM. Relevant parameters such as power loss and force induced by the eddy currents in a split cryostat were simulated using the MIM.
  
  
  CONCLUSIONS
  The proposed method is capable of accurately simulating the current diffusion process inside thin volumes, such as the magnet cryostat. The method permits the priori-calculation of optimal pre-emphasis parameters. The MIM enables unified designs of gradient coil-magnet structures for an optimal mitigation of deleterious eddy current effects.
authors.affiliation: The School of Information Technology and Electrical Engineering, The University of Queensland, Australia.
authors.forename: Hector
authors.initials: H
authors.lastname: Sanchez Lopez
authors.forename: Fabio
authors.initials: F
authors.lastname: Freschi
authors.forename: Adnan
authors.initials: A
authors.lastname: Trakic
authors.forename: Elliot
authors.initials: E
authors.lastname: Smith
authors.forename: Jeremy
authors.initials: J
authors.lastname: Herbert
authors.forename: Miguel
authors.initials: M
authors.lastname: Fuentes
authors.forename: Stephen
authors.initials: S
authors.lastname: Wilson
authors.forename: Limei
authors.initials: L
authors.lastname: Liu
authors.forename: Maurizio
authors.initials: M
authors.lastname: Repetto
authors.forename: Stuart
authors.initials: S
authors.lastname: Crozier
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D008962:Models, Theoretical; D012542:Scattering, Radiation; D014159:Transducers
keywords: eddy currents; integral method; magnetic resonance imaging